Autonomous Vehicle Maneuvering At The Limit Of Friction
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Autonomous Vehicle Maneuvering At The Limit Of Friction
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Author : Victor Fors
language : en
Publisher: Linköping University Electronic Press
Release Date : 2020-10-23
Autonomous Vehicle Maneuvering At The Limit Of Friction written by Victor Fors and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-10-23 with categories.
Without a driver to fall back on, a fully self-driving car needs to be able to handle any situation it can encounter. With the perspective of future safety systems, this research studies autonomous maneuvering at the tire-road friction limit. In these situations, the dynamics is highly nonlinear, and the tire-road parameters are uncertain. To gain insights into the optimal behavior of autonomous safety-critical maneuvers, they are analyzed using optimal control. Since analytical solutions of the studied optimal control problems are intractable, they are solved numerically. An optimization formulation reveals how the optimal behavior is influenced by the total amount of braking. By studying how the optimal trajectory relates to the attainable forces throughout a maneuver, it is found that maximizing the force in a certain direction is important. This is like the analytical solutions obtained for friction-limited particle models in earlier research, and it is shown to result in vehicle behavior close to the optimal also for a more complex model. Based on the insights gained from the optimal behavior, controllers for autonomous safety maneuvers are developed. These controllers are based on using acceleration-vector references obtained from friction-limited particle models. Exploiting that the individual tire forces tend to be close to their friction limits, the desired tire slip angles are determined for a given acceleration-vector reference. This results in controllers capable of operating at the limit of friction at a low computational cost and reduces the number of vehicle parameters used. For straight-line braking, ABS can intervene to reduce the braking distance without prior information about the road friction. Inspired by this, a controller that uses the available actuation according to the least friction necessary to avoid a collision is developed, resulting in autonomous collision avoidance without any estimation of the tire–road friction. Investigating time-optimal lane changes, it is found that a simple friction-limited particle model is insufficient to determine the desired acceleration vector, but including a jerk limit to account for the yaw dynamics is sufficient. To enable a tradeoff between braking and avoidance with a more general obstacle representation, the acceleration-vector reference is computed in a receding-horizon framework. The controllers developed in this thesis show great promise with low computational cost and performance not far from that obtained offline by using numerical optimization when evaluated in high-fidelity simulation.
Trajectory Planning For An Autonomous Vehicle In Multi Vehicle Traffic Scenarios
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Author : Mahdi Morsali
language : en
Publisher: Linköping University Electronic Press
Release Date : 2021-03-25
Trajectory Planning For An Autonomous Vehicle In Multi Vehicle Traffic Scenarios written by Mahdi Morsali and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-03-25 with categories.
Tremendous industrial and academic progress and investments have been made in au-tonomous driving, but still many aspects are unknown and require further investigation,development and testing. A key part of an autonomous driving system is an efficient plan-ning algorithm with potential to reduce accidents, or even unpleasant and stressful drivingexperience. A higher degree of automated planning also makes it possible to have a betterenergy management strategy with improved performance through analysis of surroundingenvironment of autonomous vehicles and taking action in a timely manner. This thesis deals with planning of autonomous vehicles in different urban scenarios, road,and vehicle conditions. The main concerns in designing the planning algorithms, are realtime capability, safety and comfort. The planning algorithms developed in this thesis aretested in simulation traffic situations with multiple moving vehicles as obstacles. The re-search conducted in this thesis falls mainly into two parts, the first part investigates decou-pled trajectory planning algorithms with a focus on speed planning, and the second sectionexplores different coupled planning algorithms in spatiotemporal environments where pathand speed are calculated simultaneously. Additionally, a behavioral analysis is carried outto evaluate different tactical maneuvers the autonomous vehicle can have considering theinitial states of the ego and surrounding vehicles. Particularly relevant for heavy duty vehicles, the issues addressed in designing a safe speedplanner in the first part are road conditions such as banking, friction, road curvature andvehicle characteristics. The vehicle constraints on acceleration, jerk, steering, steer ratelimitations and other safety limitations such as rollover are further considerations in speedplanning algorithms. For real time purposes, a minimum working roll model is identified us-ing roll angle and lateral acceleration data collected in a heavy duty truck. In the decoupledplanners, collision avoiding is treated using a search and optimization based planner. In an autonomous vehicle, the structure of the road network is known to the vehicle throughmapping applications. Therefore, this key property can be used in planning algorithms toincrease efficiency. The second part of the thesis, is focused on handling moving obstaclesin a spatiotemporal environment and collision-free planning in complex urban structures.Spatiotemporal planning holds the benefits of exhaustive search and has advantages com-pared to decoupled planning, but the search space in spatiotemporal planning is complex.Support vector machine is used to simplify the search problem to make it more efficient.A SVM classifies the surrounding obstacles into two categories and efficiently calculate anobstacle free region for the ego vehicle. The formulation achieved by solving SVM, con-tains information about the initial point, destination, stationary and moving obstacles.These features, combined with smoothness property of the Gaussian kernel used in SVMformulation is proven to be able to solve complex planning missions in a safe way. Here, three algorithms are developed by taking advantages of SVM formulation, a greedysearch algorithm, an A* lattice based planner and a geometrical based planner. One general property used in all three algorithms is reduced search space through using SVM. In A*lattice based planner, significant improvement in calculation time, is achieved by using theinformation from SVM formulation to calculate a heuristic for planning. Using this heuristic,the planning algorithm treats a simple driving scenario and a complex urban structureequal, as the structure of the road network is included in SVM solution. Inspired byobserving significant improvements in calculation time using SVM heuristic and combiningthe collision information from SVM surfaces and smoothness property, a geometrical planneris proposed that leads to further improvements in calculation time. Realistic driving scenarios such as roundabouts, intersections and takeover maneuvers areused, to test the performance of the proposed algorithms in simulation. Different roadconditions with large banking, low friction and high curvature, and vehicles prone to safetyissues, specially rollover, are evaluated to calculate the speed profile limits. The trajectoriesachieved by the proposed algorithms are compared to profiles calculated by optimal controlsolutions.
Proceedings Of Mechanical Engineering Research Day 2020
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Author : Mohd Fadzli Bin Abdollah
language : en
Publisher: Centre for Advanced Research on Energy
Release Date : 2020-12-01
Proceedings Of Mechanical Engineering Research Day 2020 written by Mohd Fadzli Bin Abdollah and has been published by Centre for Advanced Research on Energy this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-12-01 with Technology & Engineering categories.
This e-book is a compilation of 170 articles presented at the 7th Mechanical Engineering Research Day (MERD'20) - Kampus Teknologi UTeM (virtual), Melaka, Malaysia on 16 December 2020.
Design Modulation And Control Of Battery Integrated Modular Multilevel Converters For Automotive Applications
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Author : Arvind Balachandran
language : en
Publisher: Linköping University Electronic Press
Release Date : 2025-03-20
Design Modulation And Control Of Battery Integrated Modular Multilevel Converters For Automotive Applications written by Arvind Balachandran and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2025-03-20 with categories.
A critical component of a battery electric vehicle (BEV) is the battery pack, which has many series- and parallel-connected electrochemical cells. The total power, energy delivered, and lifetime of the battery pack are limited by the weakest cell in the pack. Battery-integrated modular multilevel converters (BI-MMC) can overcome this limitation by increasing cell-level control. BI-MMCs have several series-connected DC-to-AC converters with a battery module having a few series- and parallel-connected cells called submodules (SM). The research in this thesis focuses on the design, modulation, and control of BI-MMCs. The efficiency and adaptability of five basic BI-MMC topologies with half-bridge and full-bridge SMs across three main system configurations are presented. Full-bridge topologies offer high efficiency, some even higher than the state-of- the-art SiC two-level inverter. However, adapting them to BEVs requires significant architectural modifications to the BEV’s electrical system. The half-bridge topologies require fewer architectural modifications for adaption into the BEVs. However, they have lower efficiency and require a larger number of SMs, which increases the cost. The efficiency is increased with six-phase system configurations but at the cost of more SMs than three-phase system configurations. Another aspect of adaptability is the DC charging capabilities of BI-MMCs. The maximum DC charging power of the BI-MMCs with the same SM semiconductor losses as during traction is derived, and results show that most BI-MMCs have a maximum DC charging power of about 1MW. Key design parameters that affect the efficiency and cost of BI-MMCs are identified. They are the number of series-connected cells in an SM, SM DC-link capacitor energy, and MOSFET switching frequency. BI-MMCs with five to seven series-connected cells per SM have the highest efficiency, at an average power of 100 kW and considering phase-shifted carrier-based modulation. Selecting the MOSFET switching frequency close to the resonant frequency of the SM DC-link capacitors and the SM battery modules decreases the total efficiency. Increasing or decreasing the MOSFET switching frequency increases the efficiency but affects the loss distribution between the SM DC-link capacitors and the SM battery modules. BI-MMCs with nearest level modulation (NLM) have higher efficiencies than phase-shifted carrier-based modulation and the SiC two-level inverter. However, using NLM with low-frequency sort-and-select inter-SM balancing methods (sNLM) results in an uneven distribution of battery losses among the SMs, which may impact the thermal design. Using NLM with cyclic submodule duty cycle rotation at the fundamental frequency gives higher efficiencies than sNLM and an even distribution of battery losses among the SMs. Reconstruction of converter reference signals with a higher sample frequency at the submodule level can be used to adapt distributed control architecture to BI-MMCs. The advantage is the low communication burden between the central and the SM control units. Furthermore, the accuracy of the SM battery currents (over one fundamental period) is improved, and the output distortion is low.
Dynamics Of Vehicles On Roads And Tracks Vol 1
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Author : Maksym Spiryagin
language : en
Publisher: CRC Press
Release Date : 2017-12-06
Dynamics Of Vehicles On Roads And Tracks Vol 1 written by Maksym Spiryagin and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-12-06 with Technology & Engineering categories.
The International Symposium on Dynamics of Vehicles on Roads and Tracks is the leading international gathering of scientists and engineers from academia and industry in the field of ground vehicle dynamics to present and exchange their latest innovations and breakthroughs. Established in Vienna in 1977, the International Association of Vehicle System Dynamics (IAVSD) has since held its biennial symposia throughout Europe and in the USA, Canada, Japan, South Africa and China. The main objectives of IAVSD are to promote the development of the science of vehicle dynamics and to encourage engineering applications of this field of science, to inform scientists and engineers on the current state-of-the-art in the field of vehicle dynamics and to broaden contacts among persons and organisations of the various countries engaged in scientific research and development in the field of vehicle dynamics and related areas. IAVSD 2017, the 25th Symposium of the International Association of Vehicle System Dynamics was hosted by the Centre for Railway Engineering at Central Queensland University, Rockhampton, Australia in August 2017. The symposium focused on the following topics related to road and rail vehicles and trains: dynamics and stability; vibration and comfort; suspension; steering; traction and braking; active safety systems; advanced driver assistance systems; autonomous road and rail vehicles; adhesion and friction; wheel-rail contact; tyre-road interaction; aerodynamics and crosswind; pantograph-catenary dynamics; modelling and simulation; driver-vehicle interaction; field and laboratory testing; vehicle control and mechatronics; performance and optimization; instrumentation and condition monitoring; and environmental considerations. Providing a comprehensive review of the latest innovative developments and practical applications in road and rail vehicle dynamics, the 213 papers now published in these proceedings will contribute greatly to a better understanding of related problems and will serve as a reference for researchers and engineers active in this specialised field. Volume 1 contains 78 papers under the subject heading Road.
Optimal Braking Patterns And Forces In Autonomous Safety Critical Maneuvers
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Author : Victor Fors
language : en
Publisher: Linköping University Electronic Press
Release Date : 2019-05-02
Optimal Braking Patterns And Forces In Autonomous Safety Critical Maneuvers written by Victor Fors and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-05-02 with categories.
The trend of more advanced driver-assistance features and the development toward autonomous vehicles enable new possibilities in the area of active safety. With more information available in the vehicle about the surrounding traffic and the road ahead, there is the possibility of improved active-safety systems that make use of this information for stability control in safety-critical maneuvers. Such a system could adaptively make a trade-off between controlling the longitudinal, lateral, and rotational dynamics of the vehicle in such a way that the risk of collision is minimized. To support this development, the main aim of this licentiate thesis is to provide new insights into the optimal behavior for autonomous vehicles in safety-critical situations. The knowledge gained have the potential to be used in future vehicle control systems, which can perform maneuvers at-the-limit of vehicle capabilities. Stability control of a vehicle in autonomous safety-critical at-the-limit maneuvers is analyzed by the use of optimal control. Since analytical solutions of the studied optimal control problems are intractable, they are discretized and solved numerically. A formulation of an optimization criterion depending on a single interpolation parameter is introduced, which results in a continuous family of optimal coordinated steering and braking patterns. This formulation provides several new insights into the relation between different braking patterns for vehicles in at-the-limit maneuvers. The braking patterns bridge the gap between optimal lane-keeping control and optimal yaw control, and have the potential to be used for future active-safety systems that can adapt the level of braking to the situation at hand. A new illustration named attainable force volumes is introduced, which effectively shows how the trajectory of a vehicle maneuver relates to the attainable forces over the duration of the maneuver. It is shown that the optimal behavior develops on the boundary surface of the attainable force volume. Applied to lane-keeping control, this indicates a set of control principles similar to those analytically obtained for friction-limited particle models in earlier research, but is shown to result in vehicle behavior close to the globally optimal solution also for more complex models and scenarios.
16th International Symposium On Advanced Vehicle Control
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Author : Giampiero Mastinu
language : en
Publisher: Springer Nature
Release Date : 2024-10-03
16th International Symposium On Advanced Vehicle Control written by Giampiero Mastinu and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2024-10-03 with Transportation categories.
This open access book highlights the latest advances, innovations, and applications in the field of vehicle systems dynamics and control, as presented by leading international researchers at the 16th JSAE International Symposium on Advanced Vehicle Control (AVEC), held at Politecnico di Milano, Milan, Italy, on September 2-6, 2024. It covers a diverse range of topics such as vehicle dynamics theory, steering, brake, tire, suspension, chassis control, powertrain, electrified vehicles, stability enhancement systems, driver-vehicle systems, advanced driver assistance systems and automated driving systems, driving simulator dynamics and control. The contributions, which were selected by means of a rigorous international peer-review process, present a wealth of exciting ideas that will open novel research directions and foster multidisciplinary collaboration among different specialists.
Road Vehicle Automation 9
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Author : Gereon Meyer
language : en
Publisher: Springer Nature
Release Date : 2022-07-09
Road Vehicle Automation 9 written by Gereon Meyer and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022-07-09 with Technology & Engineering categories.
This book is the ninth volume of a sub-series on Road Vehicle Automation, published as part of the Lecture Notes in Mobility. It gathers contributions to the Automated Road Transportation Symposium (ARTS), held on July 12-15, 2021, as a fully virtual event, and as a continuation of TRB's annual summer symposia on automated vehicle systems. Written by researchers, engineers and analysts from around the globe, this book offers a multidisciplinary perspectives on the opportunities and challenges associated with automating road transportation. It highlights innovative strategies, including public policies, infrastructure planning and automated technologies, which are expected to foster sustainable and automated mobility in the near future, thus addressing industry, government and research communities alike.
The Role Of Infrastructure For A Safe Transition To Automated Driving
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Author : Adriano Alessandrini
language : en
Publisher: Elsevier
Release Date : 2021-08-10
The Role Of Infrastructure For A Safe Transition To Automated Driving written by Adriano Alessandrini and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-08-10 with Transportation categories.
The Role of Infrastructure for a Safe Transition to Automated Driving contextualizes the latest vehicle and road automation research and technology, focusing on the future role of road infrastructures. The book analyzes the problems an uncontrolled transition will pose and examines ways forward, covering risk, safety, and the influence of human factors in automated vehicles. Automated transport researchers, traffic engineers, and transport and city planners will find the book to be a great resource for addressing the complexity of the period during which both human-driven and automated cars will coexist. This integrated vision of different approaches to vehicle automation will help move the technology forward in a thought-provoking manner. - Introduces the SAE standard, the levels of automation it defines, and the concept of new road infrastructures - Addresses infrastructural and governance challenges and opportunities for automated vehicles - Includes learning tools such as chapters overviews, summaries, and a glossary
Dynamics Of Vehicles On Roads And Tracks
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Author : Maksym Spiryagin
language : en
Publisher: CRC Press
Release Date : 2021-03-18
Dynamics Of Vehicles On Roads And Tracks written by Maksym Spiryagin and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-03-18 with Technology & Engineering categories.
The International Symposium on Dynamics of Vehicles on Roads and Tracks is the leading international gathering of scientists and engineers from academia and industry in the field of ground vehicle dynamics to present and exchange their latest innovations and breakthroughs. Established in Vienna in 1977, the International Association of Vehicle System Dynamics (IAVSD) has since held its biennial symposia throughout Europe and in the USA, Canada, Japan, South Africa and China. The main objectives of IAVSD are to promote the development of the science of vehicle dynamics and to encourage engineering applications of this field of science, to inform scientists and engineers on the current state-of-the-art in the field of vehicle dynamics and to broaden contacts among persons and organisations of the various countries engaged in scientific research and development in the field of vehicle dynamics and related areas. IAVSD 2017, the 25th Symposium of the International Association of Vehicle System Dynamics was hosted by the Centre for Railway Engineering at Central Queensland University, Rockhampton, Australia in August 2017. The symposium focused on the following topics related to road and rail vehicles and trains: dynamics and stability; vibration and comfort; suspension; steering; traction and braking; active safety systems; advanced driver assistance systems; autonomous road and rail vehicles; adhesion and friction; wheel-rail contact; tyre-road interaction; aerodynamics and crosswind; pantograph-catenary dynamics; modelling and simulation; driver-vehicle interaction; field and laboratory testing; vehicle control and mechatronics; performance and optimization; instrumentation and condition monitoring; and environmental considerations. Providing a comprehensive review of the latest innovative developments and practical applications in road and rail vehicle dynamics, the 213 papers now published in these proceedings will contribute greatly to a better understanding of related problems and serve as a reference for researchers and engineers active in this specialised field.